Definition of "magnet"

Iron and coal were the magnets that drew railways to this land of lovely valleys and silent mountains—for such it was a century-and-a-half ago, before man blackened the valleys with the smoke of his forges, scarred the green hills with his shafts and waste-heaps, and drove the salmon from the quiet Rhondda and the murmuring Taff.

1939 September, D. S. Barrie, “The Railways of South Wales”, in Railway Magazine, page 157

[…] I wanted to show Nick the largest of the water holes, Rigueik, that act as magnets to life in the dry season.

2007 March, J. Michael Fay, “Ivory Wars: Last Stand in Zakouma”, in National Geographic, section 47

Regular baths will help keep your dog clean and fresh-smelling. The frequency will depend entirely on your own preferences as well as how much of a mud-magnet your dog is!

2022, Steve Mann, Easy Peasy Cocker Spaniel

Magnets are thus used to create a package of cryptologic information and bundling[sic] it together.

2019, David Adams, Ann-Kathrin Maier, Big Seven Study (2016): 7 open source Crypto-Messengers to be compared, page 142